Noncontrolling Interests (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Activity for equity attributable to noncontrolling interests
Balance at January 1	$ 153,886	$ 156,191
Net Income (Loss)	(431)	4,710	$ 19,310
Balance at December 31	146,722	153,886	156,191
Noncontrolling Interests
Activity for equity attributable to noncontrolling interests
Balance at January 1	1,170	1,163	1,314
Net Income (Loss)	66	123	69
Distributions to noncontrolling interests	(63)	(128)	(47)
Other changes, net	(7)	12	(173)
Balance at December 31	$ 1,166	$ 1,170	$ 1,163